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Trematode life cycles: short is sweet?
Robert Poulin1, Thomas H Cribb
1Dept of Zoology, University of Otago, PO Box 56, Dunedin, New Zealand. robert.poulin@stonebow.otago.ac.nz
Trends in Parasitology
|May 10, 2002
Summary
Parasitic trematodes often have complex life cycles, but many species exhibit truncation, evolving shorter cycles independently. Studying these abbreviated life cycles reveals general evolutionary forces shaping parasite development.
Area of Science:
- Parasitology
- Evolutionary Biology
- Helminthology
Background:
- Parasitic trematodes are characterized by complex life cycles involving multiple hosts.
- Life cycle truncation, involving fewer hosts and transmission events, is observed in various trematode taxa.
- This abbreviation can occur through distinct mechanisms, including extreme reduction to a single mollusc host.
Purpose of the Study:
- To review the occurrence of life cycle truncation across trematode families.
- To discuss hypotheses explaining the evolution of abbreviated trematode life cycles.
- To explore factors influencing the adoption and prevalence of shorter life cycles.
Main Methods:
- Review of existing literature on trematode life cycles.
- Phylogenetic analysis to trace independent evolution of truncation.
- Comparative analysis of different truncation strategies.
Main Results:
- Life cycle truncation has evolved independently multiple times within the phylogeny of trematodes.
- Various mechanisms contribute to life cycle shortening, including host elimination.
- Some trematodes complete their cycles using only a single mollusc host.
Conclusions:
- Shortened life cycles in trematodes are a recurring evolutionary phenomenon.
- Understanding truncation provides insights into the general evolution of life cycles.
- Further study of abbreviated cycles can illuminate evolutionary pressures on parasites.
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